N-95 masks
The most common term used now a days just after corona / covid / pandemic, is N95 mask.
The urge of gaining access to N-95 masks other than occupational requirements has created a total mess around the world. Every one is now wearing or trying to get hold of an N-95 mask.
Despite the guidelines from CDC, N-95 masks are now a crisis material for the Healthcare professionals
Why did I specified about occupational use?
N-95 mask was specifically designed for the workers at the coal mines, oil refineries or other industrial areas where public health support is compromised from the pollutants it generate.
The second most important role of this mask, is in the Health care systems.
N-95 mask is designed or manufactured for the health care professionals who are completely exposed to the infected patients in a closed environment.
Doctors, Nurses, Ambulance drivers, Para-Medic workers and those who are directly related to the crisis moment, where one or more patients are infected with a disease that may transmit through the air needs proper FDA approved N-95 mask.
This is not just a piece of clothe that we can design it like the defined mask and glue it with some stickers to call it as an N-95 mask.
Why it is called as N-95?
The most simple answer to this is it can block 95% of the microscopic particles from the air that you inhale.
Is there any other variants?
Yes there are several variants for a FFP respirator. FFP is Filtering Face Piece respirator or mask. We can categorize it in 3 different levels that are FFP1, FFP2 and FFP3.
The US standard N-95 mask is as relevant as the European FFP2 mask. The same in China is called as KN-95 mask.
NIOSH or National Institute of Occupational Safety and Health agency has categorized these highly efficient respirators in 2 main different types.
History of N-95 mask
As it claims in every aspect, necessity is the mother of invention. N-95 mask is the fruit of such an invention designed and manufactured way back during 1972.
Taking the concept of Lien Wu-teh masks were emerging in many different looks as the work demanded.
After the flu-pandemic 1918, World War I brought several modifications to a mask or a respirator. World War I gifted us the first "gas mask" to help the coal miners.
Gradually developing the concepts and modifying them during 1970, NIOSH and the Mining Bureau first time designed the concept of FFP.
In 1972, 3M is the first company to develop worlds first N-95 mask or FFP.
They have simply incorporated the concept of melt blowing process, which was by then a common procedure to manufacture bra cups, and developed the 3M- N95 mask.
The product then have gone through several modifications and research to get to this present look.
During 1995, professor Peter Tsai for the first time redefined this mask with the anti-viral technology. It proved to be an efficient face mask by preventing the drug-resistant Tuberculosis. From then this mask has gained its popularity in Health care profession.
Note: Prof. Peter Tsai recently ended his retirement and joined back to his research work for developing a COVID resistant N-95 mask.
Key components of N-95
It is a convex shaped mask with polyamide head loops.
A malleable aluminium strip positioned above the nose for a tighter seal.
The respirator is composed of 4 layers of material.
From the outer layer to the inner layer materials are
Spun-Bond Poly-propylene > cellulose or polyester > Melt blown polypropylene > spun bond polypropylene.
Processing:
Following the guidelines for a NIOSH approved N-95 mask these are the technological characteristics
The outer layer of hydrophillic plastic contains citric acid 2% w/w and pH lowering agents.
The second inner layer is treated with active metal ions, mainly Copper 1.6% w/w and Zinc 1.6% w/w
This is the main layer that traps virus in it.
The first outer layer is designed with a fairly thick polypropylene mesh with perforations.
The second layer is the stiff layer comprises large fibers of polyester.
The melt blown polypropylene layer shows the most dense network of fibers and this is the main armor trapping the sub micron particles.
The final layer, next to the users mouth, shows a complex mesh work of different size fibers.
How to qualify as an N-95 mask???
The defined mask should have a certificate of clearance for these following tests.
1) Bacterial filtration efficiency - 99.9%
2) Sub-micron particulate (0.1 um)
filtration efficiency - 99.9%
3) Differential pressure (Delta-P) - 4.9 mm of H2O / sq cm
4) Resistance to synthetic blood - 160 mm of Hg
5) Flame spread - Class I
Note: Differential pressure or Delta P is the breathability of a mask. The higher Delta P is more difficult to breathe.
Is there any other types of N-95 masks?
Unfortunately there are 2 sets of distribution to categorize a variety of N-95 masks.
Its a little bit confusing but to conclude early, lets put all these classification in short.
Mainly N-95 masks are classified according to their purpose of use.
A) Surgical N-95
B) Regular or Ordinary N-95
80% of regular N-95 masks are approved by NIOSH
80% of surgical N-95 masks are approved by FDA
The remaining 20% from the both sides are approved by NIOSH as well as FDA.
These are the only masks that a surgeon can rely upon other than the proper FDA approved surgical N-95 masks.
The basic difference is nothing but a regular N-95 mask could not pass the tests for FDA. (mentioned above)
A regular N-95 is only for particulate pollution. It cannot resist the fluid. On the other hand the Surgical mask can do both. it can protect the user from particulate pollution as well as from the fluid penetration.
A regular N-95 mask is used as an anti-pollution mask.
eg.?????
Yes of course!!! (1870+; 1860; 1860s ; 1804, 1804s)
3M N-95 mask, Model number 8210 is a standard / regular N-95 mask.
Why?? It does not have any approval from FDA as a surgical mask. And it also has no record about fluid resistance.
Worried about the surgical N-95???
3M N-95 mask Model no. 1860, and 1870(+) are examples of FDA approved, fluid resistant surgical mask/ respirator.
Note: There is a full chart available on the internet about N-95 masks model number with their FDA approval certification. Please go and check before buying.
Another option to be certain about your mask, is to cut it open and check the layers under microscope............ (I could not resist to crack this joke as I am bored too typing all this details, Ha Ha!)
Presented by,
Dr. Arka Bhattacharya
Kolkata, India
Follow the links for my next blogs about:
N-95 masks are causing hypoxia................... is it true???.
An era of Reusable N-95 masks.........................Really???
Data collected from
FDA data access
NCBI
CDC guidelines
Industrial protection guidelines
Modern Healthcare journals
Heath Leaders journals
3M company brochure
Google
Dr. Arka Bhattacharya
Good work Babai. Very informative and helpful to all. With Love and Best Wishes.
ReplyDeleteIt is important to know about what we use....N95 mask is a need in covid 19 pandemic..this is helpful..
ReplyDeleteThank you.
ReplyDeleteThank you for detailed explanation.
ReplyDeleteThank you.
Delete